A new study has found a gene that appears to make women happy, but it doesn't work for men. The finding may help explain why women are often happier than men, the research team said. Scientists at the University of South Florida (USF), the National Institutes of Health (NIH), Columbia University and the New York State Psychiatric Institute reported that the low-expression form of the gene monoamine oxidase A (MAOA) is associated with higher self-reported happiness in women. No such association was found in men.